1. Field of the Invention
The present invention relates to a semiconductor device package with a semiconductor device encapsulated therein, and, more, particularly, to a solid-state imaging device.
2. Description of the Prior Arts
Packages for semiconductor integrated circuits can be classified by type of material into three types: plastic packages using resin molding technology; ceramic packages using printed circuit ceramic substrates; glass sealed packages in which leads are sandwiched by two ceramic bodies and the assembly is sealed with low-melting point frit glass. Packages in which leads are arranged in two parallel sides of a square are called dual-in-line (DIL) packages and are the most widespread type. Hence, the aforementioned three types are also called DILP, DILC, and DILG, respectively. The DILG is also called a "cerdip" type. The manufacturing cost of three packages is high in the ascending order of DILP, DILG, and DILC, whereas reliability including moisture resistance is high in the descending order of DILC, DILG, and DILP.
Though the most distributed type for solid-state imaging devices until recently has been the DILC package with high moisture resistance, the DILG type is preferable in view of cost. An example of the DILC package is described in Japanese Laid-Open Publication No. 54(1979)-146985, while an example of the DILG is described in Japanese Laid-Open Publication No. 59(1984)-161187.
The conventional packages of solid-state imaging devices are mainly and currently of the type of DILC, and therefore the detailed structures as well as composition materials are not clarified.
By the way, a fine wire of such material as Au or Al is used for electrical connection between a semiconductor chip and leads within the package, and it is known in the semiconductor field to coat the leads with Al film so as to obtain a high bonding strength between wires and leads.
The present inventors found that the Al clad film has the above advantage but also has a serious disadvantage, especially for solid-state imaging devices.